Energy supply in the form of regenerable energy is subject to strong temporal fluctuations. While solar energy fluctuates depending on the time of the day and the season, wind energy is subject to the general weather situation and the season. The demand for energy also varies strongly depending on the time of the day and the season. Since energy supply and energy demand frequently do not coincide, suitable means for energy storage are desired in order to compensate for fluctuations and to reduce peak loads for energy generation. While heat storage strategies have developed to some extent, like gravel/water storage, storage water heater, aquifer storage, and earth storage, storage of electrical energy continues to remain particularly difficult.
Suitable hot-water heat accumulators are described, for example, in German patent reference DE OS 24 39 028. Compared with conventional large heat accumulators, these heat accumulators are supposed to avoid heat losses by dividing a storage pond into several cells using dams or separation walls so that the cells can be filled, one after the other, with hot water upon loading and with cold water upon unloading, each time by displacing one with the other.
According to German patent reference DE 42 06 695 A1, an above-ground seasonal heat energy storage can use gravel or a mixture of soil and gravel as a heat storage medium and air as a heat transport medium. The heat storage medium is thermally isolated by a layer consisting of soil and straw.
German patent reference DE 43 41 858 A1 discloses an underground heat accumulator made of soil with a heat insulating sheathing of loose rock provided with a sealing substance. Energy is obtained from, or supplied to, the soil via an energy transport device extending through the upper section of the sheathing. Water, which is used as an energy transfer medium, is supplied centrally to the heat insulated soil body and also drawn from it again.
The heat accumulators known from the state of the art are suitable to satisfy a demand for heat, e.g., for heating drinking water or for room heating, independent of supply. In this respect, the multi-chamber heat accumulator described in German patent reference DE 103 01 807 A1 does not go beyond these known heat accumulator strategies either.
It is therefore desirable to be able to use heat accumulators which, besides their use as, e.g., conventional storage water heaters, could also be used for generating electrical energy. This need and other shortcomings in the state of the art are addressed by the multi-chamber heat accumulator and method for generating electrical energy described herein.